Counterflow carburizing machine



Aug. 18, 1931. HARRls 1,819,509

COUNTERFLOW CARBURIZING MACHINE Filed March 15, 1929 2 Sheets-Sheet 1Aug. 18, 1931. H. H. HARRIS 1,819,509

COUNTERFLOW CARBURI Z ING MACHINE Filed March 15, 1929 2 Sheets-Sheet 2Patented Aug, 18, 1931 STATES HENRY H. HARRIS, OF DETROIT, MICHIGANCOUNTERFI-OW CARBURIZING MACHINE Application filed March 15, 1929.Serial No. 347,421.

I This invention relates to heat treating furnaces and has for itsobject to provide a furnace wherein heat treating or carburizing boxesmay be transported therethrough in.

such manner as to heat the boxes and contents in an even and progressivemanner whereby the contents may be subjected to temperatures in directaccord with the tem perature of the furnace and the time of exposure tothe interior thereof.

Specifically, one of the main features of the invention resides in therevision of conveying means interiorly o the furnace of suchconstruction as to maintain the heat treating boxes in suspendedrelation in order that they may be subjected to the heat of theconvection and substantially free from any heat of radiation.

Heretofore, conveyor chains or an endless succession of connected linkshave usually been employedas the conveyor, the article containing boxesbeing supported thereon for transportation through a furnace. It is seenthat the radiated heat from the conveyor links to the boxes may be andactually is transferred or radiated to the boxes at an entirelydifferent rate than is the heat of the surroundin air transferred to theboxes .by convection. T e result is that the articles w within the boxdo not receive heat in an even and progressive manner from all sides ofthe .boxes but are subjected to heat through the walls and top at onerate of absorption while an entirely difl'erent rate is set up through85 the bottom of the boxes. Of course, this rate has been computed andallowed for by vary ing the thickness of the walls of the boxes withrespect to the bottom, but it is obvious that such corrective measuresadd com lications which do not lend themselves readily to mathematicalsolution and altogether cannot be termed satisfactory for many articles.It is a "further object to provide alternate means for conveying boxesthrough my furnace without regard to their position with respect to eachother so that a box, if desired, may be carried through the furnacealone, and also to provide an arrangement employing the suspendedprinciple which is dem pendent on the furnace being filled to capacityless one box in .order to permit of travel therethrough. In other words,it is possible under the teachings of theap lication to provideactuating means for the oxes individually or to construct a massarrangement wherein a limited number of boxes receive actuation and pushother boxes in alignment therewith by an abutting relation.

A still further and important feature of this invention resides in theprovision of a furnace of the type described wherein the sus pendedboxes or containers are inserted into one end thereof, are caused totravel through the length of the furnace and return to the entering endat a different strata or elevation for removal. Specifically, thisobject depends primarily on the use of two conveyors having an elevatorfor transferring the boxes individually from one to the other of theconveyors and in placing them on a lower flight in such manner thattheir transportation continues in reverse direction, and also inadapting both types of conveyors described to this two flightarrangement.

Other flights might beadded' or merely a siigle flight might be used, ifdesired.

ther objects of the invention either directly described or indirectlyimplied will be evident to'one skilled in the art as reference is had tothe accompanying drawings wherein is illustrated one embodiment of myinvention. by way of example only, and not in a limiting sense, and inwhich Figure 1 is a side elevation of an improved type of furnaceembodying my novel conveying means, partially in section forillustrative purposes;

Figure2 is a transverse section taken along P the line 2 X of Figural;

Figure 3 is a detail view ofone roller, of

the conveyor and a track portion for cooperation therewith as attachedto a box;

Figure 4 is a modification of the detail showing of Figure 3;

Figure 5 is a further modification of the detail showing of Figures 2and 3; and

Figure 6 is a vertical section taken longitudinally through a furnaceillustrating an alternate type of conveyor.

Referring more particularly to the drawings, numeral 1 refersgenerallyto a heat treating furnace designed for a two flight conveyor and havinga door 2 for the entrance and a door 3 for the exit, which doors may beopened by any desired arrangement such as chains 4 and pulleys 5.

Extending through the side walls of the furnace are a plurality ofshafts 6 the axes of which all lie in substantially the same plane, aslight tilt being imparted to the angle of this plane if desired toassist the movement of the boxes thereover by gravity if desired. Asecond row of shafts? extends through the opposite walls and lie in aplane well below that of the shafts '6. Each of these shafts 6 and 7projects both inwardly and outwardly of the furnace walls resting insuitable bearings 8 and supporting rollers 9 interiorly of the furnaceand gear wheels 10 outwardly of the furnace. The rollers are all ofequal size and it will be seen that four rows of rollers are provided,the rowsbeing oppositely disposed in pairs while one row is well abovethe other to provide a.two flight conveyor, the flights of which may beseparated by a floor 11 extending throughout the major portion of thelength of the furnace in order to direct a flow of heat in such mannerthat it can best be utilized or taken advantage of to furnish heat tothe space adjoining the rollers in a progressive manner.

Article containing receptacles 12 are fashioned in such manner that rims13 protrude from each and to each of these rims are attached tracks 14;The rims may be formed in a variety of ways depending largely on theparticular type boxemployed, as indicated at 13 and 13 in Figures 3 and5 respectively, it being merely necessary to form the rims in such waythat a firm and reliable sup ort for the boxes be provided. The trac swhich form an integral part of the boxes may likewise assumenumerous'shapes as indicated at 14, 14' and 14" of Figure 3, 4 and 5accordin to their size and the nature of their duties, it being asalient point that the tracks be given such width as will permit alwaysof a good surface for contact with the rollers irrespective ofexpansion, contraction or warping and it is also recommended that thesetracks be attached to the rims 13, 13' and 13" with a sliding connection15 to prevent breakage upon differential expansion of these members. Theboxes are given a width in accordance with the width of the furnace sothat when they are inserted into the entrance past the door 2, thetracks 14 will ride the rollers 9. The bottoms of the boxes are wellabove the floor 11 throughout their travel over the upper flight oftheir travel and a similar s acing is provided for the bottom flight sothat the boxes are suspended throughout the time they travel through thefurnace.

It was stated that the floor 11 extends throughout the major portion ofthe length of the furnace. This floor stops'short of the whole length byan amount, preferably just a bit greater than the length of thereceptacles or boxes used so that the boxes may be lowered at the rearof the furnace to the lower conveyor. In order to accomplish thislowering, I provide a means which will now be described.

A platform having rollers 18 is attached to the plunger of an desiredtype of elevating mechanism 19 w ich might be a hydraulic jack and isgiven a range such that when in an elevated or extended position it willform a table upon which the bottom of one box at a time may roll as itstrack 14 leaves the last roller 9 of the upper flight. The box is thenlowered to a position as shown in Figure 1 where the track 14 againrests upon the rollers of the lower flight where it can resume itstravel through the furnace in a reverse direction.

Of course, it is possible to provide a stationary track in place of therollers and attach the rollers to the boxes withinthe teachings of thisapplication, however, I have illustrated the preferred arrangement andemploy the rollers held in the walls because furnace and carry gears 10,shafts 16 extend longitudinally of the sidewalls, either on one or bothsides of thefurnace, carrying worm gears 17 for driving a part or all ofthe shafts 6. These shafts 16 are driven by any suitable means as bygears 17 and electric motors 20 and 20', the motor 20 being geared tothe upper shaft 16 while motor 20' is geared to the lower shaft 17.

The operation of the motors and hence the rollers 9 are controlled bythe elevator 19, the switch 21 being moved to contact a terminal 22 bythe elevator when in an extended position so that a box will bepropelled onto the platform and rollers 16 after which the boxes of theupper flight become stationary while the box on the platform is beinglowered to the lower flight whereupon the switch lever 21 contacts theterminal 23 which starts the motor 20 and rotates the lower flight ofthe rollers 9 whereupon the box is carried oil the platform andforwardly of the furnace.

By this arrangement a single box may be taken through the furnace orboxes may be loaded at will.

According to the modification shown in Figure 6, the roller shafts donot necessarily extend through the walls of the furnace as there is nodirect driving means therefor. These rollers 9' are merely rotatablystationed in the walls in planes as described with reference toFigure 1. Plungers 24, 25 are provided to replace the longitudinal driveshafts'and electric motors. These plungers may be pneumatically orhydraulically operated. The plunger 24 is mounted at the front end oftheupper flight so that as a box is placed upon the lower flight ofrollers a piston pushes it toward the rear of the furnace. As a secondbox is placed on the rollers, a push thereon by the pistoin 26 willpropel both boxes until one box shall have attained a positiomforpropulsion upon the elevator platform and rollers 16' which is similarto that described in connection with Figure 1. Of course, I contemplatethe use of a safety device, if desired, to prevent ac tuation of thepiston 26 unless the platform is in position to properly receive thebox. As

soon as the box is lowered to a position where it rests on the lowerrollers 9' a second piston-27 may drive the box or; line of boxesforward toward the lower door.

It will be noted that the upper plunger 24 i is pivotally mounted andcounterbalanced by a weight 28 so that it may be swung out of positionfor loading of the boxes.

It will be obvious that many modifications of my invention will readilysuggest themselves to one skilled in the art and; I, therefore, desireto be limited in, the application and construction thereof only by thescope of the appended claims, wherein:

What I claim is:

1. In combination with a heat treating furnace, conveying means disposedin spaced relation above the furnace floor and providing a doublesupport at opposite sides of the furnace, and a carburizing box havingmeans projecting outwardly therefrom above the center of gravity thereofand adapted to engage said conveying means for individually supportingthe box for movement through the furnace while maintained in suspendedrelation above the floor, whereby to subject the box to heatingsubstantially by convection only.

2. In combination with a heat treating furnace., a conveyor comprisingdouble supports in spaced relation above the furnace floor along.opposite walls of the furnace, and a box having an extension thereoncontiguous to the upper end thereof, and shoe portions flexiblyconnected to said extension and engaging said supports for movement ofthe box through'the furnace while maintained in suspended relation abovethe floor.

3'.-, In combination with a heat treating furnace, article containingboxes, flanges integral with said boxes and extending outwardlytherefrom at points above the center of gravity thereof, and a movableconveyor supported in oppositely disposed walls of said furnace forsupporting the boxes individually through the flanges of said boxeswhereby the boxes may be transported through said furnace in suspendedrelation.

4. In combination with aheat treating furnace, article containing boxes,flanges integral with said boxesand extending outwardly therefromcontiguous to the upper portion thereof, and a movable conveyorsupported in oppositely disposed walls of said furnace at a fixedelevation above the.

floor for supporting the boxes individually through the flanges of saidboxes whereby the boxes may be transported through said furnace insuspended relation, said conveyor comprislng a plurality of spacedrollers rotatably mounted on shafts supported individually in the wallsof said furnace,

5. In combination with a heat treating furnace, article containingboxes, rims on said boxes supporting fiat track sections in spacedrelation with the walls of said boxes and a movable conveyor supportedin oppositely disposed walls of said furnace for engagement with saidtrack sections whereby saidboxes may, be transported through saidfurnace in suspended relation.

6. In combination with a heat treating v,

furnace, article containing boxes, rimson of, track sections ofsubstantial width attached to said projecting portionin spaced relationto the box walls and adapted to engage said conveyor supports forsuspending said boxes for movement through said furnace, said tracksections allowin expansion and contraction of said boxes as t etemperature varies without disengaging said convey-I or supports.

8. In combination with a heat treating furnace, article containing boxeshaving rims integral therewith, track sections of substantial widthattached to said rims in spaced relation with the walls of said boxes,and a movable conveyor comprising a row of rollers supported in each oftwo oppositely disposed walls of thef'furnace for reception of saidtrack sections whereby said boxes are supported in said furnace insuspended relation, said tracks by their width compensating forexpansion and contraction of the boxes under varying temperatureswhereby full support of said boxes is assured at all times.

9. In combination with a heat treating furnace, article containing boxeshaving rims integral therewith, track sections of substantial widthkeyed to said rims by means of an expansion joint, said rims alwaysmaintaining said track sections in slightly spaced relation with thewalls of said boxes and a movable conveyor comprising rows of rollerssupported in two oppositely disposed walls of the furnace for receptionof said tracks whereby said boxes are supported in said furnace insuspended relation, said expansion joint and the width of said trackscompensating for change of dimensions of said boxes and said furnaceunder varying temperature to always assure proper support of said boxesin transportation through said furnace.

10. In combination with a heat treating furnace, article containingboxes having rims integral therewith, track sections of substantialwidth attached to 'said rims in'spaced relation with the walls of saidboxes,-and a movable conveyor comprising a row of rollers supported ineach of two oppositely disposed walls of the furnace for reception ofsaid track sections whereby said boxes are supported in said furnace insuspended rela-' tion, said tracks by their width compensating forexpansion and contraction of the boxes under varying temperatureswhereby full support of said boxes is assured at all times, and meansfor limiting transverse travel of said boxes to prevent said boxesscraping the sides of the walls of said furnace.

11. In combination with a heat treating furnace, article containingboxes having rims integral therewith, track sections of substantialwidth attached to said rims in spaced relation with the walls of saidboxes, and a movable conveyor comprising a row of rollers supported ineach of two oppositely disposed walls of the furnace for reception ofsaid track section whereby said boxes are supported in said furnace insuspended relation, said tracks by their width compensating forexpansion and contraction of the boxes under varying temperature wherebyfullsupport of said boxes is assured at all times and a downwardlydepending flange integral with'said'track sections for limitingtransverse movement of said tracks with respect to said rollers.

12. In combination with a heat treating furnace, conveyor supportstherein in spaced relation above the floor of the furnace extendingalong the opposite walls thereof, boxes having integral portionsprojecting outwardly above the center of gravity thereof, track sectionsof substantial width attached by means of an expansion joint to saidprojecting portion in spaced relation to the box walls and adapted toengage said convey or supports for suspending said boxes for movementthrough said furnace, said track sections, because of the expansionjoint and the Width thereof, allowing expansion and contraction of saidboxes as the temperature varies without disengaging said conveyorsupport-s.

13. In combination with a heat treating furnace, article containingboxes having projecting portions integral therewith, track sections ofsubstantial width attached to said portions inspaced relation with thewalls of said boxes, and rollers in spaced relation above the furnacefioor extending along opposite walls of the furnace for engagement withsaid track sections for supporting the boxes in suspended-relation, saidtrack sections by their width compensating for expansion and contractionof the boxes under varying temperatures whereby full support of saidboxes is assured at all times.

14. In combination with a heat treating furnace, an upper compartmentand a lower compartment, article containing boxes, a movable conveyor insaid upper compartment and a movable conveyor in said lower compartmentfor transporting said boxes through each of said compartments, andindividual means for driving each of said conveyors and means interiorlyof the furnace for transferring said boxes individually from oneconveyor to the other. .i

15. In combination in a heat treating furnace, an upper compartment anda lower compartment, article containing boxes, a movable conveyor insaid upper compartment and a movable conveyor in said lower compartmentfor transporting said boxes through each of said compartments,individual means for driving each of said conveyors, means fortransferring said boxes individually from one conveyor to the other, andautomatic means for discontinuing the impelling means for the boxestravelling over at least one of said conveyors during the period oftransfer.

16. In combination in a heat treating furnace, an upper and a lowercompartment, article containing boxes, a conveyor in said uppercompartment and a separately drivenconveyor in said lower compartment, adoor in one end of the upper compartment for inserting said boxes ontothe conveyor therein, a door for said lower compartment below said firstnamed door and at the same end of said furnace, a passageway connectingsaid compartments in the opposite end of said furnace from said doors,the conveyor of said upper compartment being discontinued prior toextension over said passageway. a

roller bearing platform vertically operative in said passage, saidplatform when in extended position being adapted to receive the boxesfrom said upper conveyor, means for lowering said platform and therebydelivering boxes to said lower conveyor, said lower conveyor serving toadvance the boxes toward the door of said lower compartment.

17 The combination as set forth in claim 16 together with automaticmeans for dis continuing movement of the boxes on said upper conveyorpending arrival of said platform to a box receiving position withrespect thereto. 7

18. In a heat treating furnace, an upper compartment and a lowercompartment having a connecting passageway therebetween, a conveyor foreach compartment comprising rows of rollers supported in oppositelydisposed walls of said compartments, article containing boxes havingtrack carrying'rim s for suspension of said boxes on said rollers,

' the rollers in said upper compartment being discontinued at saidconnecting passageway, an elevator operating vertically in saidpassageway, rollers on said elevator for individually receiving theboxes as they leave the rollers of the upper conveyor, said elevatorbeing adapted to lower said boxes whereby the tracks carried by the rimsof said boxes rest upon the rollers of said lower conveyor which servesfor advancing boxes forwardly through said lower compartment, and. meansfor automatically restraining movement of the boxes on said upperconveyor prior to said elevator attaining a position to receive anotherbox.

19. In a heat treating furnace, a conveyor comprising a row of rollersrotatably supported by shafts mounted in the walls of the furnace,article containing boxes having track carrying rims for suspending saidboxes on said rollers, and means for impelling said boxes over saidrollers from one end of said furnace.

20. In a-heat treatment furnace, an upper compartment and a lowercompartment having a connecting passageway therebetween, heat treatmentboxes having laterally extending flanges, conveyor means fortransporting such boxes supported from said flanges through the uppercompartment,

22, In a heat treatment furnace, two chambers one over the other with aconnecting end passage, heat treatment boxes having slispending meanslocated higher than the center of gravity thereof, conveyor means fortransporting boxes supported from the suspending means through the upperchamber as far as the passageway, conveyor means extending below thepassage way for transporting such boxes supported from such suspendingmeans in reverse direction through the lower furnace chamber, and meansfor transporting the boxes down through the passageway and deliveringsame into coacting relation with said conveyor means for the lowerfurnace chamber.

In testimony whereof I aflix my signature.

HENRY H. HARRIS.

means for transporting said boxes through the passageway, and conveyormeans for transporting said boxes supported from said flanges throughthe lower compartment.

21. In a heat treating furnace, a plurality of furnace compartments witha connecting passage between successive compartments,

heat treatment boxes having suspending means above their centers ofgravity, conveyor means for transporting such boxes supported from saidsuspending means through each compartment,and means for transporting theboxes from chamber to chamber through the connecting passage.

